Probably a minor thing, however, it will save memory and give a performance increase
When the compiler comes across a string that has been +'d together, for every +, it creates a new string in memory then waits for the old string to be garbage collected
Example
let user = 'svnty';
let date = Date.now();
let str = 'hello' + user + ' the date is ' + date;
It looks as if we have put two variables into a string, but the compiler has created a new string every time it comes across a + sign
So for the str variable there has been 4 strings created in memory, only one of which is being used and the others just taking resources until out of scope
Solution
Use template literals with the back tick (or grave accent) `
Example
let user = 'svnty';
let date = Date.now();
let str = `hello ${user} the date is ${date}`;